FILE - In this June 18, 2015 file photo, Republican presidential candidate, Sen. Ted Cruz, R-Texas speaks in Washington. Cruz's recent poll results earned him a place in the first prime time Republican ... more

We think it’s interesting that months after saying Ted Cruz’s place of birth -- Canada -- wasn’t an issue, Trump has a change of heart. Why? The lead Cruz enjoys in Iowa is likely one reason. Cruz standing as the No. 1 contender is another.

But there is a third reason. This type of bluster is what has attracted those who are solidly in the Trump camp. A poll in September from Public Policy Polling showed that more than 60 percent of Trump supporters are “birthers” -- those who believe President Obama wasn’t born in the United States. More than 60 percent also believe the president is a Muslim. Not surprisingly, Trump has gone after Cruz on religion -- “not too many evangelicals come out of Cuba.”

The playbook that Trump has used to climb to the top of the GOP presidential primary field is being used on Cruz. Why not? Republican voters allowed it to work before, which is the point. Republicans have to tell Trump “no more.” They need to insist that he beats his opponent on the issues.

To his credit, Cruz responded appropriately. As the Associated Press reported, he “first reacted on Twitter, posting a link to a video from the 1970s television show ‘Happy Days’ showing the character Fonzie water skiing over a shark. The moment, known as ‘jumping the shark,’ has come to refer to the use of a gimmick to halt the decline of a television show or other effort.”

He then said he was moving “on to the issues that matter.”

At some point, the contests in Iowa and New Hampshire mercifully will be over. Republican candidates will moving south and heading toward the March 1 primaries that include Texas. They will talk more about issues that impact Texans. It is our hope that Ted Cruz’s place of birth is not one of those issues. You should demand that Trump sticks to a different script.